Summary (Post scriptum by the Editor).In the case of a55square the method of Knut Vik is essentially the sanu. as a F ishe r‐design with 6 suffices, 2 for rows and columns, 2 for the diagonal series and 2 for symmetric Knut Vik‐arrangements, where each row is moved two places to the left and to the right respectively, with respect to the previous row. The 16 D.F. for rows, columns and diagonal series are eliminated, while one of the Knut Vik‐arrangements is used for treatments and the other for error, both with 4 D.F. It might be advantageous to eleminate not only rows and columns, but also the diagonal